Document rBz7ZDj64MdOVgRkajYpQMmq7

of and 1937American Society Heating Ventilating Engineers Guide, Chapter 3--Physical and Physiological Principles of Air Conditioning Note.--Both summer and winter comfort zone9 apply to inhabitants of the United States only. Applica tion of winter comfort line is further limited to rooms heated by central station systems of the convection type*. The line does not apply to rooms heated by radiant methods. Application of summer comfort line te limited to homes, offices and the like, where the occupants become fully adapted to the artificial air con ditions. The line does not apply to theaters, department stores, and the like where the exposure is less than 3 hours. equilibrium with its environment with the least conscious sensation to the individual, or with the minimum phsyiologic demand on the heat regulat ing mechanism. This environment involves not only the condition of the' air with respect to temperature and humidity, but also the condition of the surrounding objects and wall surfaces. The comfort zone tests were made in rooms with wall surface temperatures approximately the same as the room dry-bulb temperature. For walls of large area having unusually high or low surface temperatures, however, a somewhat lower or higher range of effective temperature is required to compensate for the increased gain or loss of heat to or from the body by radiation as shown in Fig. 5. (See also Chapter 38). The average winter comfort line (66 deg ET) applies to average American men and women living inside the broad geographic belt across the United States in which' central heating of the convection type is generally used during four to eight months of the year. It does not apply to rooms heated by radiant energy, rooms with excessive glass area or rooms with poorly insulated or cold walls. Even in the warm south and southwestern climates, and in the very cold north-central climate of the United States, the comfort chart would probably have to be modified according to climate, living and working conditions, and the degree of acquired adaptation. In densely occupied spaces, such as classrooms, theaters and audi toriums, somewhat lower temperatures may be necessary than those indicated by the comfort line on account of counter-radiation between the bodies of occupants in close proximity28. The sensation of comfort, insofar as the physical environment is con< cerned, is not absolute but varies considerably among certain individuals. Therefore, in applying the air conditions indicated by the comfort line, it should not be expected that all the occupants of a room will feel per fectly comfortable. When the winter comfort line is applied in accordance with the foregoing recommendations, the majority of the occupants will be perfectly comfortable, but there will always be a few who would feel a bit too cool and a few a bit too warm. These individual differences among the minority should be counteracted by suitable clothing. Air conditions lying outside the average comfort zone but within the extreme comfort zone may be comfortable to certain persons. In other words, it is possible for half of the occupants of a room to be comfortable in air conditions outside the average comfort zone, but in the majority of cases, if not in all, these conditions will be well within the extreme comfort .zone as determined experimentally. The comfort chart (Fig. 6) applies to adults between 20 and 70 years of age living in the northeastern parts of the United States. For pre maturely born infants, the optimum temperature varies from 100 F to 75 F, depending upon the stage of development. The optimum relative humidity for these infants is placed at 65 per cent29. No data are yet available on the optimum air conditions for full term infants and young children up to school age. Satisfactory air conditions for these age groups are assumed to vary from 75 F to 68 F with natural indoor humidi ties. For school children, the studies of the New York State Commission on Ventilation place the optimum air conditions at 66 F to 68 F tempera ture: with a moderate humidity (not specified) and a moderate but not excessive amount of air movement (not specified)30. "Determination of the Comfort Zone With Further Verification of Effective Temperatures Within This Zone, by F. C. Houghten and C. P, Yaglou (A.S.H.V.E. Transactions, Vol. 29, 1923, p. 361). "The Summer Comfort Zone; Climate and Clothing, by C. P. Yaglou and Philip Drinker \ (A.S.H.V.E. Transactions, Vol. 35. 1929). \ 68 "Loc. Cit. Note 27. "Loc. Cit. Note 24. "VentilaUon (Report N. Y. State Commission on Ventilation. E. P. Dutton and Co.. N. Y.. 1923). 69